The advent of SemiRestore Lite for iOS 10.2 has opened the gateway to restore your device back to latest jailbreakable firmware without losing the jailbreak. The Lite version of the popular tool enables users to execute the commands directly from the device itself and hence it does not require your device to be connected to a computer.
With due credit to folks at Reddit, here is a simple step-by-step guide to restore your device to the last jailbreakable firmware without compromising the existing jailbreak tweaks and apps installed on your iPhone or iPad:
Step 1: Verify that MTerminal is installed on your jailbroken iOS device. If the tool is not accessible, just launch Cydia and search for MTerminal app and then install it on your iPhone or iPad.
Step 2: Ensure that your device has any file manager app like iFile or Filza installed, which allows you to communicate with your device's internal file system. Use the Cydia search feature to locate and install the app if it's not there.
Step 3: You can now download the SemiRestore10-Lite app file on your iOS device using the link posted here. By default the file should be downloaded to the /Documents folder and it is recommended that you leave it there untouched. You can use either iFile or Filza to open the downloaded file on your iPhone/iPad.
Step 4: Now launch the MTerminal app on your device and type in the "su" command. When prompted, enter the password alpine (default) for enabling super-user rights.
Step 5: Type in the following command into the terminal app and hit Enter:
cd /private/var/mobile/Documents
Step 6: Now change the permissions for the downloaded SemiRestore10-Lite file to make it executable. You need to enter the following command to accomplish this task:
chmod +x SemiRestore10-Lite
Step 7: Finally, you can execute the SemiRestore file with the following command:
./SemiRestore10-Lite
[Source: Reddit]